Elementary Differential Equations with Boundary Value Problems is written for students in science, engineering, and mathematics who have completed calculus through partial differentiation. In writing this book I have been guided by the these principles: 1. An elementary text should be written so the student can read it with comprehension without too much pain. I have tried to put myself in the student�s place, and have chosen to err on the side of too much detail rather than not enough. 2. An elementary text can�t be better than its exercises. This text includes 1695 numbered exercises, many with several parts. They range in dif�culty from routine to very challenging. 3. An elementary text should be written in an informal but mathematically accurate way, illustrated by appropriate graphics. I have tried to formulate mathematical concepts succinctly in language that students can understand. I have minimized the number of explicitly stated theorems and definitions, preferring to deal with concepts in a more conversational way, copiously illustrated by 250 completely worked out examples. Where appropriate, concepts and results are depicted in 144 �gures.